Figure 1.
Two views at 180°C of the C. perfringens Delta toxin structure in cartoon representation.
Latch domain, β-sandwich domain, Stem domain and rim domain are colored in pale cyan, cyan, red and magenta, respectively. Glycerol molecules are shown as sticks. Zinc molecules are depicted as yellow balls. Figures 1–4 are produced with PyMol.
Table 1.
Data collection and structure refinement statistics.
Figure 2.
Superposition of C. perfringens Delta toxin structure with γHL-Hlg2 in grey (PDB ID: 3B07) (A), with γHL-LukF in pale green (PDB ID: 3B07) (B) and with a monomer of the αHL of S. aureus in yellow (PDB ID: 7AHL) (C).
Colors for the different domains of C. perfringens Delta toxin have been kept as for Fig. 1. The conserved Arginine and Tryptophan associated with phospholipid binding are shown as sticks. Loops in the rim domain that differ in the various toxins are identified in (B) by their residue numbers in Delta.
Table 2.
Root-mean-square deviation in Angstroms, between the 198 Cα-atoms that have equivalents in all structures, excluding the stem domain, following Maximum-Likelihood-based multiple sequence alignment with Theseus-3D [39], [40].
Figure 3.
Model of the Delta toxin heptameric pore shown in cartoon representation with a semi-transparent surface.
Chain A is coloured cyan for the latch domain, pale green for the β-sandwich, red for the stem and raspberry for the stem domains. Remaining chains shown in single colour (pale teal, grey, lilac, pink white and yellow). (A) Top (looking down at extra-cellular face) and (B) side-view, indicating possible membrane location.
Figure 4.
C. perfringens Delta toxin structure surface from the side (A) and from the bottom of the rim domain (B).
Aliphatic residues (Ala, Val, Ile, Leu, Met) are in salmon and aromatic residues (Phe, Trp, Typ) are in red. Glycerol molecules are shown as grey sticks. In C, a cartoon representation of the glycerol molecules binding region of C. perfringens Delta toxin in cyan superposed with S. aureus LukF in lemon (PDB ID: 3LKF; [19]) and LukF-PV in pink (PDB ID: 1PVL; [20]). In D, the glycerol molecule binding region of Delta toxin, coloured as for Fig. 1 showing the residues involved in binding glycerol which are shown as lemon sticks.
Figure 5.
HeLa cells were incubated with 5 µg/ml Cy3-Delta toxin for 30min at 4°C (lane 1), 5 µg/ml for 30 min at 37°C (lane 2), or 10 µg/ml for 30 min at 37°C (lane 3) in DMEM medium containing 0.1% BSA.
After washing, the cell lysates were elctrophoresed in a SDS-containing 10% polyacrylamide gel without reducing agent and scanned for fluorescence.
Figure 6.
Electron micrographs of liposomes incubated with Delta toxin.
Scale bars correspond to 50 nm.